1. Field of the Invention
The present invention relates to a rotary compressor to be used for the refrigerators, air conditioners, and the like.
2. Related art of the Invention
Rotary compressors are much utilized for the refrigerators, air conditioners, and the like, because of their compact size and simple structure. The compression mechanism parts such as vane and roller which are the major constituting parts of the compressor are described in, for example, KAWAHIRA, "Sealed type refrigerator" (1993) P.14, FIG. 6.1.
Hereinafter, using FIG. 6, constitution and operation of the conventional rotary compressor are explained. The compression mechanism part in the sealed container comprises a crank shaft 101 having an eccentric part 109, a bearing supporting the crank shaft 101, a cylinder 102, a vane 103, and a roller 104 which eccentrically rotates in the cylinder 102. The vane 103 having a cylindrical tip reciprocates in the vane slot 105 of the cylinder 102, and its tip part is pressed to the outer peripheral surface of the roller 104 by the spring force by the spring 106 and the pressure difference between inside and outside of the cylinder 102 to slide in contact with the outer peripheral part of the roller 104, thereby dividing the inner part of the cylinder 102 into the suction chamber 107 and the discharge chamber 108. The part O is a center of the cylinder 102 and the crank shaft 101. The crank shaft 101 has an eccentric part 109 centering on the point P which is eccentric by e from the center O. The crank shaft 101 rotates centering on O, and along with it the eccentric part 109 integral with the crank shaft rotates eccentrically. The roller 104 is engaged in the eccentric part 109. Due to the rotation of the crank shaft 101 by the electric motor and the revolution of the roller 104 in the cylinder 102, refrigerant gas is taken in from the suction port 110 and sent to the discharge port 111 while being compressed. The refrigerant gas from the discharge port 111 is sent to the refrigeration cycle side through the discharge valve 112, and passed through the condenser, expansion valve, and evaporator to return to the suction port 110 of the compressor again.
In the above constitution, at the contact part between the roller 104 and the tip part of the vane 103, an oil film has been formed by the oil which is mainly contained in the intake refrigerant and the oil which passes through the gap between the vane 103 and the vane slot 105 provided on the cylinder 102 or the gap between the end face of the roller 104 by the pressure difference.
The sealed container, bearing to support the crank shaft 101, and electric motor are not illustrated.
However, according to the conventional constitution as above, as the tip part of the vane 103 has a cylindrical curved surface and the outer peripheral surface of the roller 104 is also cylindrical, the contact condition between the vane 103 and the roller 104 is equivalently the contact between the small cylinder and the large cylinder. Accordingly, the contact condition is a line contact condition wherein the contact area is smaller, and the load per unit area, i.e., contact stress, is larger, so that the contact sliding conditions between the vane 103 and the roller 104 become rigorous.
The number of autorotations of the roller 104 is also determined by the difference of the friction resistances between the inner peripheral surface and the eccentric part 109 and those between the outer peripheral surface of the roller 104 and the tip of the vane 103 and the like. The number of autorotations of the roller 104 is very unstable. In general, when the crank shaft 101 is operated at the revolution of 3500 rpm, the number of autorotations of the roller is about several scores to several hundreds rpm.
Because of the above, on the sliding surfaces of the tip of the vane 103 and the roller 104 the sliding speeds vary depending on conditions, and sliding movements become unstable.
Moreover, there is a problem that, in case of the use of the chlorine-free alternative refrigerant, e.g., R134a, remarkable lowering of lubrication occurs, and especially in case of the rotary compressor, wear is apt to occur between the outer periphery of the roller 104 and the tip of the vane where an oil film is less apt to be formed.
In order to settle the above points, for example, Japanese Patent Laid-open HEI 7-259767 discloses such construction that there are a horizontal hole 116 thrusting through the inside of the crank shaft 101 and its eccentric part 109 from the oil feed passage 115 to the outer diameter of the eccentric part 109, an oil groove 117 provided on the outer diameter part of said eccentric part 109 in communication with the horizontal hole 116, a groove 121 provided on the outer periphery of the roller 104, a hole 120 thrusting through said outer peripheral groove 119 provided in parallel with said groove 119 at the deepest part of the groove 119 and a vane 103 is applied to the groove 119.
According to said constitution, the contact between the roller 104 with the vane 103 becomes face contact and the autorotation of the roller 104 is also restricted, and stable sliding conditions can be realized. However, the oil supply to the contact part between the roller 104 and the vane 103 becomes intermittent because the hole 120 thrusting through from the inner diametrical part of the roller comes to be communicated with the side hole 116 provided to lead to the outer diametrical part of the eccentric part from the oil supply passage 115 only once in a turn. Therefore, no sufficient oil is supplied. Another drawback is that the oil to be supplied to the sliding part between the eccentric part 109 and the inner periphery of the roller 104 shows decrease.
In the first invention, in consideration of the points of the conventional compressors as shown in FIG. 7, an object is to provide a highly reliable, long life rotary compressor by reduced sliding load between the vane and the roller and supply of sufficient oil to the sliding part between the vane and the roller.
On the other hand, according to the constitution of the conventional compressor as in the above FIG. 7, the sliding conditions between the vane 103 and the roller 104 are improved, but the oil supply to the contact part between the roller 104 and the vane 103 involves drawbacks due to the complicated routes intervened by many relay points as described above, thus requiring complicated processing, having tendency to cause pooling of gases and difficulty of stabilized oil supply. Moreover, there has been no consideration given to the measures to be taken against the extremely large force applied to the inner peripheries of the eccentric part 109 and the roller 104 from the latter half part of the compression process.
The second invention is to settle the points of the conventional compressor of FIG. 7. It aims at providing a more reliable, long life rotary compressor which is easily processed, does not give ill affect on other sliding part, assures stabilized oil supply, and permits reliable sliding and lubrication between the vane and the roller.
On the other hand, with respect to the groove part 119 of the conventional compressor shown in FIG. 7 above, as shown in FIG. 17, in case of the contact sliding between the tip R part of the vane 103 and the groove 119 of the roller 103 according to the eccentric rotation of the roller 104, if there are always or temporarily in the groove 119 the edge 122 on the suction chamber 107 side of the vane 103 and the edge 123 on the discharge chamber 108 side (the edge refers to the crossing part between the R part and the side surface), they have possibility to wear the groove part 119. Also, due to the pressure difference between the suction chamber 107 side of the vane 103 and the discharge chamber 108 side, at the groove part 119 the surface pressure on the suction chamber 107 side becomes higher than on the discharge chamber 108 side. Accordingly, the sliding movement conditions become severer on the suction chamber 107 side edge 122 than on the discharge chamber 108 side edge 123. The parts 124 and 125 are the shoulders of the groove 119, and the part 126 is a center of the part R of the vane 103.
With the object of solving the points of the conventional compressor as shown in FIG. 7, the third invention aims at providing a highly reliable rotary compressor wherein prevention is made of the contact sliding between at least the edge on the suction chamber side of the vane with the groove.
An object of the fourth invention is to provide, in order to solve the points of the conventional compressor as shown in FIG. 7, a more highly reliable, long life rotary compressor with reduced load of the sliding part between the vane and the roller, and assured lubrication of the sliding part between the vane and the roller, by realizing the constitution of separate embodiment from the third invention.
Recently, with the object of protecting ozone layer, there has come to be used a chlorine-free alternative refrigerant (e.g., R-134a). In the conventional compressor of FIG. 7, such a chlorine-free alternative refrigerant gives further unsatisfactory sliding condition in comparison with the refrigerant containing chlorine. Accordingly, it is necessary to provide severer restriction on the conditions for the use of the compressor or to develop a sliding material having improved abrasion resistance performance.
The first to the fourth inventions referred to above are each intended to solve the points of the conventional compressors as above.